The present invention relates to an earth working machine, such as a road milling machine, a recycler, a stabilizer, or a surface miner and the like. The earth working machine encompasses a machine body having a machine frame and a drive configuration rotationally drivable around a drive axis relative to the machine frame. The drive axis defines an axial direction. The earth working machine further encompasses a working apparatus for earth working to which the drive configuration is releasably connected in drive torque-transferring fashion for rotation together. The working apparatus extends axially between a drive axial end and a retention axial end located oppositely from the drive axial end, and radially externally surrounds the drive configuration of the earth working machine. The working apparatus is retained on the drive configuration, against axial displacement relative to the drive configuration, by way of a central bolt arrangement that is accessible in the region of its retention axial end and has a bolt axis collinear with the drive axis.
An earth working machine of this kind, in the form of an earth milling machine, is known from DE 10 2012 008 252 A1. This document discloses a milling drum constituting a working apparatus, which is retained in the region of its retention axial end by way of a threaded rod screwed at the end into the drive configuration, and a retaining nut in bolting engagement therewith. The milling drum of the known earth milling machine is pushed axially with the retaining nut against a tooth set in a region located closer to the drive axial end of the milling drum. A drive torque is transferable by the tooth set from the drive configuration to the milling drum.
The axial positional retention of the milling drum relative to the drive configuration as known from DE 10 2012 008 252 A1 is disadvantageous in terms of its retaining effect. Because of the use of a threaded rod screwed at the end into the drive configuration and a retaining nut in bolting engagement with the threaded rod, upon release of axial positional retention is not possible to predict the point at which the bolt arrangement begins to loosen upon exertion of a loosening torque (release moment). On the one hand, the threaded rod together with the retaining nut can be unscrewed from the drive configuration as a bolt arrangement moving together; on the other hand, the retaining nut can move relative to the threaded rod so that the threaded rod constitutes, with the drive configuration, an arrangement which is connected for movement together and relative to which the retaining nut is movable.
Lastly, as a function of differences in friction conditions, caused e.g. by dirt, upon exertion of a release moment, both the one and the other situation can occur, so that in portions the threaded rod is unscrewed from the drive configuration, and in portions the retaining nut is moved relative to the threaded rod. In either case, exertion of a loosening torque does not result in an unequivocally predictable machine state.
The same can be true, mutatis mutandis, for a tightening torque (tightening moment) in a retaining direction, although the possibility that exists here, in contrast to loosening, is firstly to screw in the threaded rod and only then bolt on the retaining nut.
In addition, because of the dimensions of the known retaining nut, the torque that can be exerted on the bolt arrangement of the known milling drum upon tightening and loosening using conventional tools, for example a torque wrench, is limited. It is noteworthy here that earth-removing working apparatuses in particular are exposed, while being operated as intended, to very large force inputs that an axial positional retention system must withstand. Reliable establishment, and also reliable release, of axial positional retention for a working apparatus of an earth working machine is therefore the focus of the present Application.
The present invention therefore also relates to a method for establishing or releasing axial positional retention of a working apparatus of an earth working machine on a drive configuration of the earth working machine, in particular of the earth working machine recited above. The drive configuration is rotatable around a drive axis relative to a machine frame of the earth working machine. The working apparatus radially externally surrounds the drive configuration, axial positional retention being effected by a central bolt arrangement having a bolt axis collinear with the drive axis.
Because of the potentially very large reaction forces that occur depending on the kind of working, and that feed back into the working apparatus in the context of earth working, axial positional retention of the working apparatus on the drive configuration with a tightening torque of more than 2500 Nm is desirable in order to furnish sufficient operating reliability. Applying such a large retaining torque to the bolt arrangement of the earth milling machine known from DE 10 2012 008 252 A1 is cumbersome, and requires tools that are usually available only in workshops but not at the utilization site of the machine.